[HarfBuzz] Regression with ZWJ in Indic scripts

[Behdad Esfahbod]

BTW, how do you pass OpenType script tag to HarfBuzz?!

On 13-03-18 03:15 PM, Khaled Hosny wrote:
> The issue reported below seems to be a regression in 0.9.13, basically
> ZWJ seems to be completely ignored, with 0.9.12 I get the desired
> output.
> 
> Regards,
> Khaled
> 
> ----- Forwarded message from Ian-Mathew Hornburg <imhornburg at gmail.com> -----
> 
> From: Ian-Mathew Hornburg <imhornburg at gmail.com>
> To: xetex at tug.org
> Subject: [XeTeX] Incorrect Bengali ZWJ behavior and v2 script spec
> Reply-To: Unicode-based TeX for Mac OS X and other platforms <xetex at tug.org>
> 
> I may have identified two possible bugs in 0.9999.0: the release notes
> indicate that the version-2 OpenType Indic script tags are now supported,
> and I’ve been testing various Bengali-script fonts with the git version of
> XeTeX and a current install of TeX Live 2012 to check them for correct
> shaping behavior. I’ve posted a MWE reproducing some examples from the
> Microsoft standard here: [http://pastebin.com/mgAX8c7U].
> 
> Microsoft ships two Bengali fonts (Vrinda and Shonar Bangla; both v6.80)
> with Windows 8 that support both the older (beng) and newer (bng2) Bengali
> script specs. (Older versions of each are shipped with Windows 7 and other
> Microsoft products.) The fonts behave correctly when using the beng script
> feature, with the exception of a particular ZWJ sequence: the Microsoft
> spec [https://www.microsoft.com/typography/OpenTypeDev/bengali/intro.htm]
> says that the sequence of consonant-hasant-ZWJ-consonant should prevent a
> ligature of the two consonants, then render a half-form of the first
> consonant. XeTeX currently fails to suppress the ligature.
> 
> ----- End forwarded message -----
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-- 
behdad
http://behdad.org/